Communication device and communication method

Abstract

To provide a technique for appropriately maintaining the power consumption and voice quality of a communication device in response to changes in communication quality.SOLUTION: A transmitting unit 130 transmits a plurality of packet signals each including an audio signal per unit time to another communication device. A receiving unit 160 receives error rate information when the other communication device receives the plurality of packet signals. A control unit 120 calculates the number of packets to be deleted from the plurality of packet signals based on the received error rate information, and determines the number of a plurality of packet signals to be transmitted from the transmitting unit 130 per unit time. A generating unit 122 includes the audio signal in the plurality of packet signals determined by the control unit 120, and then outputs the signals to the transmitting unit 130.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to communication technology, and particularly to a communication device and a communication method for transmitting voice signals.

Background Art

[0002] Some transmitters that perform wireless communication using the TDMA (Time Division Multiple Access) method are equipped with a call interruption function that stops data transmission in response to a request from the receiver (hereinafter also referred to as "transmission interruption instruction") during a call with the receiver. So far, when the transmitter stops data transmission in a predetermined time slot, a technique has been proposed in which the transmitter selects voice data for the time slot in which data transmission is interrupted from a plurality of non-consecutive sections in the voice data to suppress deterioration of voice quality (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a communication device including such a transmitter, it is required to appropriately maintain the power consumption during transmission and the voice quality with respect to changes in communication quality.

[0005] The present invention has been made in view of such a situation, and an object thereof is to provide a technique for appropriately maintaining the power consumption and voice quality of a communication device with respect to changes in communication quality.

Means for Solving the Problems

[0006] To solve the above problems, a communication device according to an aspect of the present invention includes a transmission unit that transmits a plurality of packet signals per unit time including an audio signal to another communication device, a reception unit that receives error rate information when the other communication device receives the plurality of packet signals transmitted from the transmission unit, a control unit that calculates the number of deletion packets to be deleted from among the plurality of packet signals based on the error rate information received by the reception unit and determines the number of the plurality of packet signals per unit time to be transmitted from the transmission unit, and a generation unit that outputs to the transmission unit after including the audio signal in the plurality of packet signals determined by the control unit. When the error rate information is equal to or less than a first threshold value, the control unit increases the number of deletion packets by a predetermined number, and when the error rate information is equal to or greater than a second threshold value, the control unit decreases the number of deletion packets by a predetermined number.

[0007] Another aspect of the present invention is a communication method. This method includes a step of transmitting a plurality of packet signals per unit time including an audio signal to another communication device, a step of receiving error rate information when the other communication device receives the plurality of packet signals transmitted, a step of calculating the number of deletion packets to be deleted from among the plurality of packet signals based on the received error rate information and determining the number of the plurality of packet signals per unit time to be transmitted, and a step of including the audio signal in the determined plurality of packet signals. The determining step increases the number of deletion packets by a predetermined number when the error rate information is equal to or less than a first threshold value, and decreases the number of deletion packets by a predetermined number when the error rate information is equal to or greater than a second threshold value.

[0008] In addition, any combination of the above components, and those obtained by converting the expression of the present invention among a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as aspects of the present invention.

Effects of the Invention

[0009] According to the present invention, it is possible to appropriately maintain the power consumption and audio quality of the communication device with respect to changes in communication quality.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 7

Mode for Carrying Out the Invention

[0011] Before specifically describing this embodiment, first, an overview will be described. This embodiment relates to a communication system including two communication devices that execute a voice call. Here, it is assumed that one of the two communication devices (hereinafter referred to as the "first communication device") transmits a voice signal, and another one of the two communication devices (hereinafter referred to as the "second communication device") receives the voice signal. The case where the second communication device transmits a voice signal and the first communication device receives the voice signal will be omitted from the description. In such a communication system, it is required to appropriately maintain power consumption and voice quality with respect to changes in communication quality.

[0012] The first communication device according to this embodiment includes an audio signal in a plurality of packet signals and transmits the plurality of packet signals to a second communication device. The second communication device measures the error rate of the received packet signals and transmits the measurement result to the first communication device as error rate information. The first communication device calculates the number of packet signals not to be transmitted (hereinafter, also referred to as "deleted packets") in the error rate information. Specifically, when the error rate information is lower than the threshold value, that is, when the communication quality is high, the first communication device increases the number of deleted packets. On the other hand, when the error rate information is higher than the threshold value, that is, when the communication quality is low, the first communication device decreases the number of deleted packets. As the number of deleted packets increases, since transmission is not performed, power consumption is reduced, and as the number of deleted packets decreases, the number of packets to be deleted decreases, so that deterioration of audio quality is suppressed.

[0013] FIGS. 1(a)-(b) are diagrams showing the configuration of the communication system 1000. The communication system 1000 includes a first communication device 100a and a second communication device 100b generically called a communication device 100. Here, the number of communication devices 100 included in the communication system 1000 is "2", and the first communication device 100a and the second communication device 100b are directly connected. However, the number of communication devices 100 included in the communication system 1000 may be more than "2". Also, a plurality of communication devices 100 may be connected via a base station device. In that case, TDMA-based communication is performed between the plurality of communication devices 100 and the base station device. Communication may be performed by other methods.

[0014] In FIG. 1(a), the first communication device 100a transmits an audio signal 10 to the second communication device 100b. The second communication device 100b measures the error rate of the audio signal 10. The second communication device 100b transmits the measured error rate to the first communication device 100a as error rate information 20. The first communication device 100a reflects the received error rate information 20 and transmits the next audio signal 10 to the second communication device 100b.

[0015] In Fig. 1(b), the second communication device 100b transmits the voice signal 10 to the first communication device 100a. The first communication device 100a measures the error rate of the voice signal 10. The first communication device 100a transmits the measured error rate to the second communication device 100b as error rate information 20. The second communication device 100b reflects the received error rate information 20 and transmits the next voice signal 10 to the first communication device 100a.

[0016] When a call is made between the user using the first communication device 100a and the user using the second communication device 100b, the processes of Fig. 1(a) and Fig. 1(b) are combined. In this embodiment, the case of Fig. 1(a) is described as above. In the case of Fig. 1(b), the first communication device 100a and the second communication device 100b may be reversed compared to the case of Fig. 1(a).

[0017] Fig. 2 is a diagram showing an example of the configuration of the communication device 100 according to the embodiment. The communication device 100 includes a microphone 110, a control unit 120, a transmission unit 130, an antenna switching unit 140, an antenna 150, a reception unit 160, a speaker 170, and a storage unit 180. The control unit 120 includes a generation unit 122 and a measurement unit 124.

[0018] The microphone 110 of the first communication device 100a converts the user's voice into an analog signal. Further, the microphone 110 converts the analog signal into a digital signal (hereinafter referred to as "voice signal") and outputs the voice signal to the control unit 120.

[0019] The generation unit 122 performs voice encoding processing on the voice signal input from the microphone 110 using a vocoder or the like, and arranges the encoded voice signal (hereinafter also referred to as "voice signal"), synchronization data, and control data at positions specified by the communication protocol to form a frame. Further, the generation unit 122 removes components in unnecessary bands from the voice signal using a filter. The frame is also called a packet signal.

[0020] Figs. 3(a)-(c) are diagrams for explaining the outline of voice signal processing in the communication device 100. As shown in Fig. 3(a), the generation unit 122 compresses the data amount by performing voice encoding processing on the voice signal input from the microphone 110 in units of 20 ms. The voice signals in units of 20 ms are denoted as "A", "B", ···.

[0021] Fig. 3(b) shows the processing following Fig. 3(a). As shown in Fig. 3(b), the generation unit 122 combines four compressed voice signals, synchronization data, and control data to generate one frame of 80 ms of data (packet signal). The synchronization data is a unique pattern for the second communication device 100b to synchronize with the frame timing, and the control data indicates the transmission source and destination IDs. The generation unit 122 continues the transmission state by repeatedly executing this frame generation during transmission. Also, a superframe including four frames is defined. Fig. 3(c) will be described later, and we return to Fig. 2.

[0022] The transmission unit 130 modulates the packet signal generated by the generation unit 122 and transmits the packet signal of the RF signal (hereinafter, this is also referred to as the "packet signal") to the antenna switching unit 140. That is, the transmission unit 130 transmits a plurality of packet signals including voice signals per unit time. The unit time may be arbitrarily defined, and here, as an example, it is set to four superframes.

[0023] The control unit 120 controls the transmission operation and reception operation in the communication device 100. The control unit 120 is connected to the antenna switching unit 140. The control unit 120 controls the antenna switching unit 140 to connect the antenna 150 to the transmission unit 130 during transmission. Also, the control unit 120 controls the antenna switching unit 140 to connect the antenna 150 to the reception unit 160 during reception. The antenna switching unit 140 is controlled by the control unit 120 and connects the antenna 150 and the transmission unit 130 during transmission. The antenna 150 transmits the packet signal to the second communication device 100b.

[0024] The antenna switching unit 140 of the second communication device 100b is controlled by the control unit 120 and connects the antenna 150 and the receiving unit 160 during reception. The receiving unit 160 receives a packet signal from the first communication device 100a via the antenna 150. The receiving unit 160 demodulates the packet signal.

[0025] The control unit 120 performs removal of signal components in unnecessary bands by a filter, bit detection, and error correction on the packet signal received from the receiving unit 160. Specifically, as shown in FIG. 3(c), after synchronizing the frame timing with the synchronization data, the control unit 120 decodes the control data and, if it confirms that the data is addressed to itself, sequentially decodes the voice signal following the control data. The decoded voice signal (hereinafter also referred to as "voice signal") is denoted as "A", "B",... Returning to FIG. 2.

[0026] The speaker 170 converts the voice signal from the control unit 120 from a digital signal to an analog signal and outputs the voice converted from the analog signal.

[0027] The measurement unit 124 measures the error rate of the packet signal in the control unit 120. Since a known technique may be used for measuring the error rate, the description is omitted here. The generation unit 122 outputs the error rate measured by the measurement unit 124 to the transmission unit 130 as error rate information. The error rate information may be included in the aforementioned control data. The transmission unit 130, the antenna switching unit 140, and the antenna 150 perform the same processing on the error rate information as on the packet signal and transmit the error rate information to the first communication device 100a.

[0028] The antenna switching unit 140 of the first communication device 100a is controlled by the control unit 120 and connects the antenna 150 and the receiving unit 160 during reception. The receiving unit 160 receives error rate information from the second communication device 100b via the antenna 150. This error rate information is the error rate information when the second communication device 100b receives a plurality of packet signals transmitted by the transmitting unit 130 of the first communication device 100a. The receiving unit 160 demodulates the error rate information.

[0029] Based on the error rate information, the control unit 120 determines the number of packet signals per unit time to be transmitted from the transmitting unit 130, for example, the number of packet signals per 4 superframes. Here, the processing when the number of packet signals is reduced will be described while using FIGS. 4(a)-(c). FIGS. 4(a)-(c) are diagrams for explaining the outline of another voice signal processing in the communication device 100 according to the embodiment. FIG. 4(a) is the same as FIG. 3(a). As shown in FIG. 4(a), the generation unit 122 compresses the data amount by performing voice encoding processing on the voice signal input from the microphone 110 in units of 20 ms. The voice signals in units of 20 ms are denoted as "A", "B", ···.

[0030] FIG. 4(b) is the processing following FIG. 4(a). As shown in FIG. 4(b), the generation unit 122 combines four compressed voice signals, synchronization data, and control data to generate one-frame data (packet signal) of 80 ms. At that time, the generation unit 122 does not store the voice signal "D" in the frame, but instead stores the next voice signal "E" in the frame. As a result, the voice signal "D" that was not stored is not transmitted from the first communication device 100a. If the generation unit 122 performs the same processing in subsequent frames, a total of four voice signals (D, H, L, P) are not stored in the frame per superframe (4 frames). Since the four voice signals match the number of voice signals stored in one frame, the transmission of the fourth frame is paused. As a result, the power consumption of the first communication device 100a is reduced. The frame to be paused for transmission may be predetermined. The frame to be paused for transmission corresponds to the aforementioned "deleted packet". FIG. 4(c) will be described later and we will return to FIG. 2.

[0031] When the error rate information is equal to or less than the first threshold, the control unit 120 decreases the number of a plurality of packet signals per unit time. This corresponds to increasing the number of deletion packets. When the error rate information is equal to or greater than the second threshold, the control unit 120 increases the number of a plurality of packet signals per unit time. The upper limit of the packet signals to be increased is the sum of the number of a plurality of packet signals per unit time, which is the case where no deletion packet is set. This corresponds to decreasing the number of deletion packets, and the number of reduction packets is a packet number of 0 or more. The first threshold is set to a value smaller than the second threshold. When the error rate information is greater than the first threshold and smaller than the second threshold, the control unit 120 does not change the number of a plurality of packet signals per unit time. This corresponds to not changing the number of deletion packets.

[0032] Figs. 5(a)-(d) are diagrams for explaining an outline of still another audio signal processing in the communication device 100 according to the embodiment. In Figs. 5(a)-(d), four superframes are shown. Fig. 5(a) shows a case where 16 packet signals are transmitted per four superframes. This corresponds to the case where no deletion packet is set per four superframes. Fig. 5(b) shows a case where 15 packet signals are transmitted per four superframes. This corresponds to the case where one deletion packet is set per four superframes. Fig. 5(c) shows a case where 14 packet signals are transmitted per four superframes. This corresponds to the case where two deletion packets are set per four superframes. Fig. 5(d) shows a case where 12 packet signals are transmitted per four superframes. This corresponds to the case where four deletion packets are set per four superframes. Here, the superframes including deletion packets are arranged to be dispersed. When the number of deletion packets increases, the power consumption decreases, but the quality of the reproduced audio deteriorates. Therefore, in the present embodiment, in order to appropriately maintain the power consumption and the audio quality with respect to changes in the communication quality, the number of deletion packets is calculated according to the error rate information.

[0033] The generation unit 122 includes an audio signal in a plurality of packet signals for which the control unit 120 has calculated the number of deleted packets. At this time, the number of deleted packets calculated by the control unit 120 is included in the control data. Since the subsequent processing is the same as before, the description is omitted here.

[0034] After the control unit 120 of the second communication device 100b that has received a plurality of packet signals from the first communication device 100a synchronizes with the frame timing using the synchronization data as shown in FIG. 4(c), if it decodes the control data and confirms that it is data addressed to itself, it sequentially decodes the audio signals following the control data. At this time, the audio signals (D, H, L, P) not transmitted in each frame are interpolated. For interpolation, for example, an audio interpolation function provided in the vocoder is used.

[0035] In addition to the above processing, the first communication device 100a may execute the following processing. The storage unit 180 stores the history of the reception time and the error rate information received by the reception unit 160. Specifically, the storage unit 180 stores the correspondence between the reception time of the error rate information and the error rate information. The control unit 120 calculates the number of deleted packets for each time using the error rate information, the first threshold value, and the second threshold value in the history. Further, the storage unit 180 may store the history of the time at the time of transmission from the transmission unit 130 and the number of deleted packets. Specifically, the storage unit 180 stores both or either one of the correspondence between the transmission time and the error rate and the correspondence between the transmission time and the number of deleted packets. The control unit 120 calculates the number of deleted packets for each time using both or either one of the error rate information and the number of deleted packets in the history. This corresponds to generating a pattern of the number of deleted packets based on the history stored in the storage unit 180.

[0036] The generation unit 122 includes the voice signal 10 in a plurality of packet signals based on the current time and the number of deletion packets indicated by the pattern generated by the control unit 120 at the same time on the day after the next day, and then outputs the signals to the transmission unit 130. At this time, the control unit 120 stops comparing the error rate information with the first threshold value and the second threshold value. However, the receiving unit 160 of the first communication device 100a continues to receive the error rate information from the second communication device 100b. When the error rate information becomes equal to or higher than the third threshold value, the control unit 120 may stop using the above-described pattern and resume determining the number of deletion packets by comparing the error rate information with the first threshold value and the second threshold value. A value larger than the second threshold value is set as the third threshold value.

[0037] This configuration can be realized by the CPU, memory, and other LSIs of an arbitrary computer in terms of hardware, and can be realized by a program loaded in the memory in terms of software. However, here, the functional blocks realized by their cooperation are depicted. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by only hardware, only software, or a combination thereof.

[0038] The operation of the communication system 1000 with the above configuration will be described. FIG. 6 is a sequence diagram showing the communication procedure by the communication system 1000 according to the embodiment. For example, the first threshold is set to 15%, and the second threshold is set to 20%. The first communication device 100a transmits the voice signal 10 to the second communication device 100b with the number of deleted packets being "1" (S10). The second communication device 100b transmits error rate information with an error rate of 10% to the first communication device 100a (S12). Since the first communication device 100a calculates it as "2" with the number of deleted packets increased because it is 15% or less set by the first threshold, it transmits the voice signal 10 to the second communication device 100b (S14). The second communication device 100b transmits error rate information with an error rate of 25% to the first communication device 100a (S16). Since the first communication device 100a calculates it as "1" with the number of deleted packets decreased because it is 20% or more set by the second threshold, it transmits the voice signal 10 to the second communication device 100b (S18). The second communication device 100b transmits error rate information with an error rate of 10% to the first communication device 100a (S20).

[0039] FIG. 7 is a flowchart showing the communication procedure by the communication device 100 according to the embodiment. The control unit 120 sets the number of deleted packets to, for example, "1" (S50). The transmission unit 130 transmits the voice signal 10 (S52). The reception unit 160 receives the error rate information (S54). When the error rate information is less than or equal to the first threshold (Y in S56), the control unit 120 increases the number of deleted packets (S58). When the error rate information is not less than or equal to the first threshold (N in S56) and the error rate information is greater than or equal to the second threshold (Y in S60), the control unit 120 decreases the number of deleted packets (S62). When the error rate information is not greater than or equal to the second threshold (N in S60), the control unit 120 maintains the number of deleted packets.

[0040] According to this embodiment, based on the error rate information, the number of deleted packets is calculated and the number of a plurality of packet signals per unit time is determined. Therefore, if the error rate information is low, the number of a plurality of packet signals per unit time is decreased, so that an increase in power consumption can be suppressed. Further, based on the error rate information, the number of deleted packets is calculated and the number of a plurality of packet signals per unit time is determined. Therefore, if the error rate information is high, the number of a plurality of packet signals per unit time is increased, so that a degradation in voice quality can be suppressed. Further, based on the error rate information, the number of deleted packets is calculated and the number of a plurality of packet signals per unit time is determined. Therefore, power consumption and voice quality can be appropriately maintained with respect to a change in communication quality. Further, based on the history of the number of deleted packets, a pattern of the number of a plurality of packet signals per unit time is generated, so that the processing can be simplified. Further, a plurality of the generated patterns may be combined to determine the number of a plurality of packet signals per unit time.

[0041] As described above, the present invention has been described based on the embodiments. In the embodiments, the voice signal has been described, but the present invention is not limited thereto, and an information signal such as a data signal may be used. It is to be understood by those skilled in the art that these embodiments are illustrative, and that various modifications are possible in combinations of their respective components and each processing process, and that such modifications are also within the scope of the present invention.

[0042] The control unit 120 of the first communication device 100a in this embodiment increases or decreases the number of deleted packets by "1" using the first threshold value and the second threshold value. However, the present invention is not limited thereto. For example, the control unit 120 may increase or decrease the number of deleted packets by "2" using more threshold values. According to this modification, the degree of freedom of the configuration can be improved.

[0043] The control unit 120 of the first communication device 100a in this embodiment calculates the number of deleted packets based on the received error rate information. However, it is not limited to this. For example, the control unit 120 of the second communication device 100b may calculate the number of deleted packets based on the error rate information. In that case, the second communication device 100b may transmit the calculated number of deleted packets to the first communication device 100a, and the first communication device 100a may use the received number of deleted packets. According to this modification example, the degree of freedom in configuration can be improved.

Description of Reference Numerals

[0044] 10 Voice signal, 20 Error rate information, 100 Communication device, 110 Microphone, 120 Control unit, 122 Generation unit, 124 Measurement unit, 130 Transmission unit, 140 Antenna switching unit, 150 Antenna, 160 Reception unit, 170 Speaker, 180 Storage unit, 1000 Communication system.

Claims

1. A transmitting unit that transmits a plurality of packet signals per unit time including an audio signal to another communication device; A receiving unit that receives error rate information when the other communication device receives the plurality of packet signals transmitted from the transmitting unit; A control unit that calculates the number of deletion packets to be deleted from among the plurality of packet signals based on the error rate information received by the receiving unit, and determines the number of the plurality of packet signals per unit time to be transmitted from the transmitting unit; A generating unit that outputs to the transmitting unit after including an audio signal in the plurality of packet signals determined by the control unit; The control unit increases the number of deletion packets by a predetermined number when the error rate information is equal to or less than a first threshold value, and decreases the number of deletion packets by a predetermined number when the error rate information is equal to or more than a second threshold value. A communication device.

2. The communication device further includes a storage unit that stores a history of the error rate information and the number of deletion packets received by the receiving unit; The control unit generates a pattern that is a relationship between time and the number of deletion packets based on the history stored in the storage unit, calculates the number of the deletion packets based on the current time and the pattern, and transmits from the transmitting unit. Determine the number of the plurality of packet signals per unit time to be used; The communication device according to claim 1.

3. Transmitting a plurality of packet signals per unit time including an audio signal to another communication device; Receiving error rate information when the other communication device receives the plurality of packet signals transmitted; Calculating the number of deletion packets to be deleted from among the plurality of packet signals based on the received error rate information, and determining the number of the plurality of packet signals per unit time to be transmitted; Including an audio signal in the determined plurality of packet signals; In the determining step, when the error rate information is equal to or less than a first threshold value, the number of deletion packets is increased by a predetermined number, and when the error rate information is equal to or more than a second threshold value, the number of deletion packets is increased. A communication method for decreasing the number of deletion packets by a predetermined number.

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